Codicil

A codicil is a supplement to a Will used to make a small change — such as swapping an executor, adjusting a bequest, or adding a beneficiary — without rewriting the whole document. It must be signed and witnessed with the same formalities as a Will, and it is read together with the original. Because codicils can create ambiguity or get separated from the Will, most modern estate planners simply prepare a fresh Will instead.

A codicil is most useful for a single, clear change where re-executing the entire Will would be inconvenient. Example: after his named executor moves overseas, Tom signs a codicil appointing his daughter as substitute executor while leaving the rest of his Will unchanged. Like a Will, a codicil can be revoked, and it is automatically affected by revocation of the underlying Will.